Feeding teats are placed on bottles that are used to feed infants and children. Turbulence in flow of liquid proximate the teat outlet (which is in the nipple of the teat) can cause the introduction of air bubbles which are then swallowed by the infant. Additionally, the amount of work (suction) required to draw the liquid from the teat can cause the infant to take in additional air by breaking the latch (seal between lips and outside of the teat). Regardless, air intake causes discomfort, and can be a source of “colic.” Also, in typical teats the contents of the liquid (minerals/vitamins and sometimes solids in solution or in a thin slurry) can settle or be pushed away from the liquid in the solution depending on the pattern of flow.
When infants suck on typical teats they must learn to pause periodically to let air into the bottle so as to equalize the pressure in the bottle. This can cause frustration. Some teat designs include valves that are meant to channel air from outside (atmosphere) into the bottle during suck (negative pressure). This air may be kept away from the feeding zone and prevent a vacuum from forming in the bottle. The valves integrated into the teat add to the complexity and expense of the teat. Also, these valves may not be sufficiently functional.